A track-type undercarriage system utilizes track rollers, which are usually mounted in some fashion to the track frame, to support and guide the track. Generally, these track roller mounting systems fall into one of two categories. The first category is the traditional track roller mounting system, in which the rollers are mounted to the track roller frame rails at both free ends of the shaft of the rollers. That is to say, a shaft is connected to two parallel frame rails at its free ends and two roller treads are provided in-between the frame rails to engage two parallel shoe roller paths of the track. The second category is the cantilevered track roller mounting system, in which the rollers hang away from a single frame rail by a shaft whose sole free end is attached to the rail.
The traditional track roller mounting system has some disadvantages. First, the presence of two rails and caps that are typically used to mount the shaft to the rails make access to the track and rollers for cleaning difficult. This may lead to mud packing and the like over time that can cause wear on various components of the undercarriage. Second, the lack of access may make it more difficult to inspect and service various components of the undercarriage. Third, there is limited flexibility as to where and how many track rollers can be mounted to act as bottom track rollers. This may lead to a load distribution from the track to the track rollers that is less than optimal. A fourth problem is that caps and the bolted joint that hold them onto the rail, capturing the shaft of the rollers, may move or “work” over time causing wear on the components, leading to a loose bolted joint that can result in undesirable maintenance of the equipment.
The cantilevered track roller mounting system can improve on many of the advantages just described with respect to the traditional track roller mounting system. However, since the double set of rollers are only mounted at one end, the stresses resulting from the overhang on the shaft can be greater than the stresses exerted on the shaft of a traditional track roller mounting system. This results in the need to make sure that the cantilevered track roller mounting system is sufficiently robust to ensure good reliability and durability of the undercarriage.